Integrated Gasification Combined Cycle (IGCC) systems are an economically attractive alternative to Natural Gas Combined Cycle systems (NGCC), as the systems can use more abundant fuel sources such as coal or biomass. IGCC systems gasify the low heating value fuel and produce a mixture comprising hydrogen and carbon monoxide. IGCC systems also have greater potential for efficiency improvement and a decrease in undesirable emissions compared to conventional coal-fired steam power plants.
IGCC power plants having oxygen-blown gasifiers to generate syngas require a relatively pure stream of oxygen gas. Production of this oxygen supply can be achieved by various means. A well-known technique is the cryogenic air separation method, in which the partial pressure differences between oxygen and other air constituents is exploited at a very low temperature and an elevated pressure to effect phase differences that are used to separate the air components. One disadvantage of using cryogenic systems for oxygen separation is that the compression stage requires significant power consumption. This reduces the plant output and net efficiency. Another air separation technology involves use of an Ion Transport Membrane (ITM) to remove oxygen from a high temperature, pressurized air stream. The resulting ITM system output streams are: (i) an oxygen-enriched gas supply delivered at a high temperature and ambient pressure, and (ii) an oxygen-depleted air supply delivered at a high temperature and a high pressure. A compressor and an air pre-heater are generally employed to provide the high temperature, high pressure air stream, adding significant equipment installation and operational cost for deployment of the ITM technology in IGCC systems.
In accord with common practice, the various described device features are not drawn to scale, but are drawn to emphasize specific features relevant to the invention. Like reference characters denote like elements throughout the figures and text.